TWI798204B - Black near-infrared reflective pigment and method for producing same - Google Patents

Abstract

The present invention provides a method for producing a black near-infrared reflective pigment containing at least calcium, titanium, and manganese that has less elution of calcium or manganese due to contact with an acid. At least a calcium compound, a titanium compound, and a manganese compound are mixed and fired by a wet pulverization method, and the BET specific surface area is 1.0 m ² /g or more and less than 3.0 m ² /g. And, as another method, a bismuth element and/or an aluminum element are contained in a black near-infrared reflective pigment containing at least a calcium element, a titanium element, and a manganese element.

Description

Black near-infrared reflective pigment and manufacturing method thereof

The present invention relates to a black near-infrared reflective pigment and a manufacturing method thereof.

The near-infrared reflective pigment is a material that reflects near-infrared rays contained in sunlight or the like. If the pigment is applied to ground surfaces or buildings covered with asphalt or cement, etc., since it can reduce the amount of infrared rays absorbed by them, it can alleviate the heat island phenomenon or improve the cooling efficiency of buildings in summer.

As a black-based near-infrared reflective pigment, the present inventors have proposed perovskite-type composite oxides containing at least alkaline earth metal elements, titanium elements, and manganese elements (eg, Patent Documents 1 and 2).

In Patent Document 1, a perovskite-type composite oxide infrared reflective pigment containing at least alkaline earth metal elements, titanium elements, and manganese elements is proposed, and the BET specific surface area is preferably about 0.05-80 m ² /g. Furthermore, in the examples, the raw materials are fully mixed with an agate mortar and then fired to produce manganese-containing calcium titanate with a specific surface area of 0.32-1.54 m ² /g. Also, in the same way, calcium carbonate containing aluminum and manganese with an Al/Ti molar ratio of 0.007~0.04 and a specific surface area of 0.50~1.23m ² /g can also be produced.

In Patent Document 2, as a perovskite-type composite oxide containing at least alkaline earth metal elements, titanium elements, and manganese elements, one with a BET specific surface area of preferably 3.0 to 150 m ² /g is proposed, which has excellent hiding power or coloring power. Black-based near-infrared reflective pigment. Furthermore, in the examples, the raw materials were mixed with a wet pulverizer to produce calcium titanate containing aluminum and manganese with an Al/Ti molar ratio of 0.007 and a specific surface area of 4.3-8.7 m ² /g. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2010-202489 [Patent Document 2] International Publication No. 2015/080214

[Problem to be solved by the invention]

The pigments described in Patent Documents 1 and 2 are black and have excellent near-infrared reflection properties, but the alkaline earth metal elements or manganese elements of the constituents are easily eluted when contacted with acid, and the color tone of the pigments may change accordingly, or The problem of gloss reduction (hereinafter this issue is also collectively referred to as "improvement of acid resistance"). Therefore, when used outdoors in an acidic environment such as acid rain, or when used indoors, further improvements in acid resistance are required for near-infrared reflective pigments. When used indoors, it may be exposed to an acidic environment due to the entry of acidic pollutants in the atmosphere. [Means to solve the problem]

As a result of active research by the present inventors in view of the aforementioned problems in the prior art, it was found that at least a compound of calcium element, a compound of titanium element, and a compound of manganese element were mixed and fired by a wet pulverization method, and the BET specific surface area In the range of 1.0 m ² /g or more and less than 3.0 m ² /g, a black near-infrared reflective pigment with improved acid resistance can be obtained, and thus the present invention has been completed. In addition, it is also found that the acid resistance can be further improved by containing a specific amount of aluminum and/or bismuth in the black near-infrared reflective pigment containing calcium, titanium and manganese.

That is, the present invention includes the inventions of the following (1) to (11). (1) A black near-infrared reflective pigment, which contains at least calcium element, titanium element, manganese element, and bismuth element, with a perovskite (perovskite) phase as the main phase. (2) The black near-infrared reflective pigment as in (1), wherein the atomic content of bismuth element ([Bi]) is relative to the sum of the atomic content of titanium element ([Ti]) and the atomic content of manganese element ([Mn]) The atomic ratio ([Bi]/([Ti]+[Mn])) is 0.02 or less. (3) The black near-infrared reflective pigment as in (1) or (2), which contains at least calcium element, titanium element, manganese element, bismuth element, and aluminum element, and has a perovskite phase as the main phase. (4) A black near-infrared reflective pigment as in (3), wherein the atomic content of the aluminum element ([Al]) is relative to the sum of the atomic content of the titanium element ([Ti]) and the atomic content of the manganese element ([Mn]) The atomic ratio ([Al]/([Ti]+[Mn])) is 0.1 or less. (5) The black near-infrared reflective pigment according to any one of (1) to (4), which has a BET specific surface area of 1.0 m ² /g or more and less than 3.0 m ² /g. (6) A production method, which is a production method of a black near-infrared reflective pigment that mixes at least a calcium compound, a titanium compound, and a manganese compound by a wet pulverization method, and is fired at a temperature higher than 1100°C. The aforementioned black near-infrared ray The reflective pigment is based on a perovskite phase, and its BET specific surface area is more than 1.0 m ² /g and less than 3.0 m ² /g. (7) The method for producing a black near-infrared reflective pigment according to (6), comprising mixing at least a calcium compound, a titanium compound, a manganese compound, and an aluminum compound by a wet pulverization method, and firing. (8) The method for producing a black near-infrared reflective pigment as described in (6), comprising at least mixing and firing calcium compounds, titanium compounds, manganese compounds, and bismuth compounds by wet pulverization. (9) The method for producing a black near-infrared reflective pigment as described in (6), comprising at least mixing and firing calcium compounds, titanium compounds, manganese compounds, aluminum compounds, and bismuth compounds by wet pulverization. (10) The method for producing a black near-infrared reflective pigment as in (7) or (9), wherein in the black near-infrared reflective pigment, the atomic content of the aluminum element ([Al]) is relative to the atomic content of the titanium element ([Ti] ) to the atomic content of manganese ([Mn]) and the atomic ratio ([Al]/([Ti]+[Mn])) of 0.1 or less. (11) The method for producing a black near-infrared reflective pigment as in (8) or (9), wherein the atomic content of bismuth element ([Bi]) is relative to the atomic content of titanium element ([Ti]) and the atomic content of manganese element The atomic ratio ([Bi]/([Ti]+[Mn])) of the sum of ([Mn]) is 0.02 or less. [Invention effect]

The present invention is a simple method of mixing and firing raw material compounds by wet pulverization, and adjusts the BET specific surface area within a specific range to produce black near-infrared reflective pigments with improved acid resistance. Moreover, by containing aluminum and/or bismuth in the black near-infrared reflective pigment containing calcium, titanium and manganese, it is possible to manufacture a black near-infrared reflective pigment with further improved acid resistance. The aforementioned black near-infrared reflective pigment has a BET specific surface area within a specific range and has a large particle size, so it is easy to disperse in solvents and is easy to prepare in dispersions, paints, inks, etc. Moreover, it can be mixed into the resin to form it, and can be mixed into the fiber during spinning, so it can be easily fixed on the spinning surface, and can be easily used according to the application.

The black near-infrared reflective pigment of the present invention has the following features. (1) The crystal structure is dominated by the perovskite phase. Examples of the perovskite phase include an ABO ₃ type structure, a layered perovskite type structure (n(ABO ₃ )·AO), and the like. In the present invention, it is a composite oxide in which A contains at least calcium element and B contains at least titanium element and manganese element. O represents an oxygen element, and theoretically there are three or more, but actual pigments may be lacking.

The presence of a perovskite phase can be confirmed by powder X-ray diffraction. When Cu-Kα is used as a line source, the ABO _3- type perovskite phase mainly composed of calcium, titanium and manganese shows major Diffraction peak. Also, the positions of these peaks can vary within a range of about ±1.5° depending on the composition. For example, regarding the ratio of the titanium element to the manganese element, as the manganese element increases, the peak position shifts to the high angle side.

The so-called perovskite phase as the main phase means that the largest peak in the powder X-ray diffraction pattern belongs to the perovskite phase mainly composed of calcium, titanium and manganese elements. When the aforementioned calcium, titanium and manganese elements are the main constituents of the ABO _3- type perovskite phase, the peak around 2θ=33.5° is the main peak. In the present invention, it is also possible to produce a wave peak belonging to the CaTiO ₃ phase or the CaMnO ₃ phase. In this case, the main peak intensity is preferably 0.1 or less relative to the main peak intensity of the aforementioned ABO _3- type perovskite phase mainly composed of calcium, titanium, and manganese. It is better to produce a perovskite single phase mainly composed of calcium, titanium and manganese.

The atomic ratio of manganese to titanium (the so-called atomic ratio refers to the ratio of the number of atoms (number of atoms), that is, the molar ratio of each atom, also known as the "molar ratio"), in the titanium element The atomic content (atomic number) is recorded as [Ti], and when the manganese atomic content (atomic number) is recorded as [Mn], it is recorded as [Mn]/[Ti], and the atomic ratio [Mn]/[Ti] is preferably The range of 0.5~2, more preferably the range of 0.8~1.2. If [Mn]/[Ti]≧0.5, it can be a near-infrared reflective pigment with high blackness and less red tone. When [Mn]/[Ti]≦2, the near-infrared reflectance can be sufficiently improved. In this case, the number of atoms (number of atoms) is referred to as the "atomic content" or "mole number" of the atom, also referred to as "content" for short.

(2) Blackness The near-infrared reflective pigment of the present invention has high blackness and can be preferably used as a black pigment. Specifically, the brightness index L value of the Hunter Lab color space (Lab color system) (called the Hunter L value, the smaller the value, the stronger the blackness) can be expressed as 20 or less. In particular, the L value may be 13 or less. The powder color can be obtained by thoroughly pulverizing the sample in an agate mortar, putting the sample into a 30mmφ aluminum ring, applying a load of 9.8MPa, and pressing to form it. system) measurement.

When the a value of the aforementioned Lab color system is -5~5, the red tone can be suppressed to a low level, and the a value can also be around -0.5~1.5. Furthermore, when the b value of the Lab colorimetric system is about -0.5 to 1.0, the yellowish tint can be suppressed to become black.

(3) Near-infrared reflective properties The near-infrared reflective properties of the powder of the black near-infrared reflective pigment of the present invention expressed by the reflectance to a wavelength of 1200nm may be 57% or 63%. As shown in the examples, acid resistance and near-infrared reflection properties can be combined to a high degree in the present invention. Shows high near-infrared reflection properties when used as a coating film. Specifically, the solar reflectance (value calculated from the spectral reflectance using the valence coefficient described in JIS K 5602) in the wavelength range of 780 to 2500 nm may be 35% or more, and may be 40% or more.

(4) Preferred additive 1 (aluminum element and/or bismuth element) The above-mentioned black near-infrared reflective pigment of the present invention containing at least calcium element, titanium element and manganese element preferably contains aluminum element and/or bismuth element.

When aluminum is contained, the atomic ratio (molar ratio) of its content relative to the sum of the content of titanium (Ti) and manganese (Mn) is preferably represented by [Al]/([Ti]+[Mn]) It is 0.1 or less, more preferably 0.01≦[Al]/([Ti]+[Mn])≦0.1. Here, [Al] represents the molar number of aluminum element, [Ti] represents the molar number of titanium element, and [Mn] represents the molar number of manganese element. When [Al]/([Ti]+[Mn]) is 0.01 or more, the effect of improving the acid resistance is confirmed, and when it is 0.015 or more, the effect is more clear. From this point of view, the more preferable value may be 0.03 or more. However, when the aluminum element is too much, the a value becomes high and has a reddish tinge. In addition, since the particles become hard, a large amount of energy must be invested in order to adjust the particle size by pulverization. Furthermore, when it is used for paints and the like, the dispersibility tends to decrease. When [Al]/([Ti]+[Mn]) is 0.1 or less, there is probably no problem, and 0.07 or less is appropriate. Although the existence state of aluminum element is not clear, if [Al]/([Ti]+[Mn]) is less than 0.1, no clear peak attributed to Al compound can be seen by powder X-ray diffraction, so it is presumed to be solid. Soluble in the perovskite phase.

When bismuth is contained, the atomic ratio (molar ratio) of its content relative to the sum of the content of titanium (Ti) and manganese (Mn) is represented by [Bi]/([Ti]+[Mn]) It is preferably at most 0.1, more preferably 0.002≦[Bi]/([Ti]+[Mn])≦0.02. Here, [Bi] represents the molar number of bismuth element, [Ti] represents the molar number of titanium element, and [Mn] represents the molar number of manganese element. When [Bi]/([Ti]+[Mn]) is 0.002 or more, the effect of improving the acid resistance is clearly observed. However, when the bismuth element content is too high, a different phase is formed, and the near-infrared reflectance also starts to decrease along with this. [Bi]/([Ti]+[Mn]) is probably no problem if it is 0.02 or less, and it is more preferably 0.01 or less. Although the existence state of bismuth element is not clear, if [Bi]/([Ti]+[Mn]) is less than 0.01, no clear peak attributed to the Bi compound can be seen by powder X-ray diffraction, so it is presumed to be solid. Soluble in the perovskite phase. When both the aluminum element and the bismuth element are contained, each atomic ratio (molar ratio) mentioned above may be contained. When the aluminum element is contained, the BET specific surface area is preferably at least 1.0 m ² /g and less than 3.0 m ² /g. On the other hand, when the bismuth element is contained, or when the bismuth element and the aluminum element are contained, the BET specific surface area is preferably at least 1.0 m ² /g and less than 3.0 m ² /g, but not limited thereto, and may be 1.0 m ² The range of not less than /g and not more than 10m ² /g.

In addition to calcium compounds, titanium compounds, and manganese compounds, aluminum compounds can also be mixed and fired by the wet pulverization method described later. By containing aluminum element, the acid resistance can be further improved. This is considered to be due to the fact that the crystal instability caused by the unbalanced atomic valence or defects in the crystal is reduced by adding aluminum. As an aluminum compound, aluminum hydroxide, aluminum oxide, etc. can be used, for example. If the aluminum compound is pre-precipitated on the surface of the particles of titanium oxides, hydrated oxides, hydroxides, etc., or pre-existed inside the particles, the aluminum element is likely to exist inside the particles of the perovskite-type composite oxide. better. The method is not particularly limited, and a known method can be used.

Furthermore, in addition to calcium compounds, titanium compounds, and manganese compounds, bismuth compounds can also be mixed and fired by the wet pulverization method described later. By containing bismuth element, the acid resistance can be further improved. This is considered to be due to the fact that the crystal instability caused by the unbalanced atomic valence or defects in the crystal is reduced by adding bismuth. As the bismuth compound, for example, bismuth hydroxide or bismuth oxide can be used.

(5) Preferred additives 2 (alkaline earth metal elements, magnesium elements, rare earth elements) The method for producing the black near-infrared reflective pigment of the present invention described above may further include (that is, use together) strontium and Compounds of alkaline earth metal elements such as barium or compounds of magnesium elements or compounds of rare earth elements such as yttrium are mixed and fired by wet pulverization. As an alkaline earth metal compound, a rare earth compound, or a magnesium compound, oxides, hydroxides, carbonates, etc. of these can be used. In particular, when a compound of magnesium element and a compound of calcium element are used in combination, near-infrared reflection performance can also be improved. The content of magnesium can be appropriately set according to the desired performance such as near-infrared reflection energy, and the molar ratio between magnesium (Mg) and alkaline earth metals and rare earth elements (A ₁ ) is preferably 1.0×10 ^-6 ≦[Mg]/ [A ₁ ]≦0.20, more preferably 1.0×10 ^-6 ≦[Mg]/[A ₁ ]≦0.12. Here, [Mg] represents the number of moles of magnesium element, and [A ₁ ] represents the number of moles of alkaline earth metals and rare earth elements. In addition, the molar ratio between calcium (Ca) and alkaline earth metals, magnesium, and rare earth elements (A ₂ ) other than calcium is preferably 0.8≦[Ca]/[A ₂ ], more preferably 0.9≦[Ca] /[A ₂ ]. Here, [Ca] represents the number of moles of calcium element, and [A ₂ ] represents the number of moles of alkaline earth metals, rare earth elements, and magnesium elements other than calcium. Also, "・" used here means "and/or". Therefore, for example, the above "alkaline earth metals other than calcium and rare earth elements" only need to contain at least one element among alkaline earth metals other than calcium and rare earth elements, and the above "alkaline earth metals other than calcium and rare earth elements・Magnesium element” only needs to contain at least one element among alkaline earth metal elements other than calcium, rare earth elements, and magnesium elements.

(6) Preferable additive 3 (group 13 element of the periodic table or zinc element) The method for producing the black near-infrared reflective pigment of the present invention described above may further include the 13th element of the periodic table other than aluminum such as boron, gallium, indium, etc. Compounds of group elements or zinc compounds are mixed and fired by wet pulverization. By containing these elements, near-infrared reflection performance can be further improved. As compounds of these elements, oxides, hydroxides, carbonates and the like of each element can be used. When these compounds are mixed and the amount of these compounds is small, it is preferable to pre-exist on the particle surface and/or inside the particle of the titanium compound, and it is easy to obtain a homogeneous black near-infrared reflective pigment in which the solid-phase synthesis reaction proceeds uniformly. Based on this, on the surface of compound particles such as titanium oxides, hydrated oxides, and hydroxides, compounds of Group 13 of the Periodic Table or zinc compounds are pre-precipitated, or when they are pre-existed inside the particles, the compounds of Group 13 of the Periodic Table It is preferable that the element or zinc element easily exists inside the particles of the perovskite-type composite oxide. The method is not particularly limited, and a known method can be used.

The Group 13 elements of the periodic table other than aluminum such as boron, gallium, indium, etc. need only exist on the surface and/or inside of the particles of the perovskite-type composite oxide, and preferably exist in the particles of the perovskite-type composite oxide internal. The content of these elements (group 13 elements of the periodic table other than aluminum) can be appropriately set according to the performance of the desired near-infrared reflection energy, etc., preferably the sum of the content of titanium (Ti) and manganese (Mn) and the The atomic ratio (molar ratio) of such elements (Ga) is contained in such an amount that 0.0005≦[Ga]/([Ti]+[Mn])≦1.5. Here, [Ga] represents the number of moles of elements in Group 13 of the periodic table other than aluminum, [Ti] represents the number of moles of titanium elements, and [Mn] represents the number of moles of manganese elements. If the value of the atomic ratio (molar ratio) [Ga]/([Ti]+[Mn]) is in the range of 0.0005~1.5, it has excellent near-infrared reflection, so it is better, more preferably 0.001≦[ Ga]/([Ti]+[Mn])≦0.45, more preferably 0.005≦[Ga]/([Ti]+[Mn])≦0.35, preferably 0.005≦[Ga]/[Ti]≦ 0.25. If the value of [Ga]/([Ti]+[Mn]) is more than 0.0005, the additive effect will be seen, and if the value of [Ga]/([Ti]+[Mn]) is less than 1.5, no effect will be seen produced out of phase.

The zinc element only needs to exist on the surface and/or inside of the particles of the perovskite-type composite oxide, and is preferably present inside the particles of the perovskite-type composite oxide. The content of zinc element can be appropriately set according to the expected performance of near-infrared reflection energy, etc., preferably the atomic ratio (molar ratio) of the sum of the content of titanium element (Ti) and manganese element (Mn) to zinc element (Zn) It is contained in an amount of 1.0×10 ^-6 ≦[Zn]/([Ti]+[Mn])≦0.20. Here, [Zn] represents the molar number of zinc element, [Ti] represents the molar number of titanium element, and [Mn] represents the molar number of manganese element. If the value of the atomic ratio (molar ratio) [Zn]/([Ti]+[Mn]) is in the range of 1.0×10 ^-6 ~0.20, it has excellent near-infrared reflection, so it is better, more preferably 1.0×10 ^-6 ≦[Zn]/([Ti]+[Mn])≦0.15, more preferably 1.0×10 ^-6 ≦[Zn]/([Ti]+[Mn])≦0.12. If the value of [Zn]/([Ti]+[Mn]) is above 1.0×10 ^-6 , the additive effect will be seen, and if the value of [Zn]/([Ti]+[Mn]) is below 0.20, There is no significant change in the formation of different phases or the color of the powder.

When the black near-infrared reflective pigment of the present invention has an ABO ₃ type perovskite structure, the content of the aforementioned calcium and the alkaline earth metals, rare earths, and magnesium elements other than the aforementioned calcium added as needed is set to a mole, and the titanium element, When the total content of manganese element, periodic table group 13 element and/or zinc element added as needed is b mole, it is preferable to adjust the ratio a/b to be 0.9≦a/b≦1.4. If it is within this range, sufficient near-infrared reflection performance is exhibited. If it is in the range of 0.9≦a/b≦1.1, even if fired at a relatively low temperature, it is less likely to become a phase other than the perovskite structure, which is more preferable.

Calcium element, titanium element, manganese element contained in the black near-infrared reflective pigment, and aluminum element, bismuth element, alkaline earth metal element other than calcium element, rare earth element, magnesium element, and periodicity other than aluminum element The amount of elements in group 13 and zinc in the table can be obtained by fluorescent X-ray analysis.

Unavoidable impurities derived from various raw materials may be mixed in the black near-infrared reflective pigment of the present invention. In this case, Cr is preferably contained as much as possible, and even if it is contained as an impurity, it is preferably 1% by mass or less, and the content of Cr ⁶⁺ , which is especially a safety concern, is preferably 10 ppm or less. Moreover, it is also preferable not to contain the unreacted residue of a raw material as much as possible, and it is especially preferable that it is 1 mass % or less.

The second invention is a method for producing a black near-infrared reflective pigment, which is to mix at least a calcium compound, a titanium compound and a manganese compound by a wet pulverization method, and burn at a temperature higher than 1100°C. The black near-infrared reflective pigment The main phase is perovskite phase, and the BET specific surface area is more than 1.0m ² /g and less than 3.0m ² /g.

In the second invention, the BET specific surface area of the manufactured black near-infrared reflective pigment is 1.0 m ² /g or more and less than 3.0 m ² /g. Mixing of raw materials is carried out by wet pulverization and firing, and when the specific surface area is within the above range, acid resistance can be improved, that is, the dissolution of constituent components can be suppressed even in an acidic environment, and the accompanying color change and gloss can be obtained Reduces suppressed black NIR reflective pigments. Compared with dry mixing and grinding, wet mixing and grinding can reduce the agglomeration of each raw material powder, especially manganese dioxide raw material powder, because it can uniformly mix raw materials with different particle sizes (calcium compound, manganese compound, titanium compound), so It is believed that it can reduce the crystal instability caused by the unbalanced atomic valence or the existence of defects in the crystal. If the mixing of raw materials is not carried out by the wet pulverization method, the acid resistance cannot be easily improved even if the BET specific surface area is within the above range. When the raw materials are mixed by the wet pulverization method and the BET specific surface area is 3.0 m ² /g or more, the acid resistance is insufficient. From the viewpoint of acid resistance, the BET specific surface area is preferably at most 2.6 m ² /g, more preferably at most 2.1 m ² /g. On the other hand, considering the near-infrared reflection characteristics and dispersibility, the BET specific surface area is not less than 1.0 m ² /g and not more than 3.0 m ² /g, preferably not less than 1.5 m ² /g and not more than 2.6 m ^{2 /} g. g or less, more preferably not less than 1.6 m ² /g and not more than 2.1 m ² /g. If so, in addition to the excellent acid resistance, the dispersibility when formulated into the coating can be further improved, and a black near-infrared reflective material with excellent blackness and higher near-infrared reflective properties can be obtained. That is, acid resistance and near-infrared reflection characteristics and dispersibility, which are in a trade-off relationship, can be balanced in an overall high region. The BET specific surface area can be obtained by one-point method of nitrogen adsorption.

The black near-infrared reflective pigment obtained by the production method of the present invention can be easily disintegrated by disintegrating after firing. Furthermore, it has good dispersibility when it is made into a paint or mixed with a resin, and high-quality paint or resin can be obtained. At the same time, it can also improve the near-infrared reflectance when modified in the coating film. This tendency is particularly remarkable when the BET specific surface area is 1.6 m ² /g or more. As shown in the examples, both acid resistance and dispersibility can be achieved to a high degree in the present invention. By mixing the raw materials by the wet pulverization method, the agglomeration of each raw material powder, especially the manganese dioxide raw material powder can be reduced and uniform mixing is possible, so it is presumed to be an effect. Specifically, the degree of dispersion measured by a particle size meter may be less than 20 μm, preferably less than 10 μm. The assay method is described in detail in the examples.

As the calcium compound, calcium oxide, calcium hydroxide, calcium carbonate and the like can be used. As titanium compounds and manganese compounds, individual oxides, hydroxides, carbonates, etc. can be used. These raw materials are weighed to a specific composition.

Next, mix the aforementioned raw materials by wet pulverization. Mixing by wet pulverization can be performed by known methods. For example, a method using a wet pulverizer is exemplified. As the wet pulverizer, known machines can be suitably used. Wet pulverizers using pulverization media such as wet ball mills, wet bead mills, sand mills, media agitation mills, etc., or agitation mills, disc mills, on-line mills, wet jet mills can be used Wet pulverizers that do not use pulverizing media. If the present invention uses a wet pulverizer such as a wet ball mill, a wet bead mill, etc. using a pulverizing medium, it can reduce the aggregation of each raw material powder, especially the manganese dioxide raw material powder, and can uniformly mix raw materials with different particle sizes (calcium Compounds, manganese compounds, titanium compounds) have high effects and are particularly good. The wet pulverizer may be any of a circulation type, a passing type, and a batch type. The residence (crushing) time and number of passes of the wet pulverizer can be appropriately set according to the equipment capacity. In order to increase the crushing strength, conventional crushing media such as alumina or zirconia can be used. It is better to adjust the diameter of the crushing medium appropriately, for example, one with a diameter of about 0.001~1mm can be used. The filling rate of the grinding medium in the wet grinding machine is also preferably adjusted appropriately, for example, it can be set to a volume ratio of about 10-90%. Any solvent may be used for the dispersion medium used in the wet pulverization method of the present invention. Examples thereof include water, alcohol, and the like, and water is preferably used. In the present invention, a dispersant may be added during wet pulverization, and for example, polymer dispersants such as polyoxyalkylene-based and polycarboxylic acid-based are preferably used. The amount of dispersant added can be set appropriately.

In the present invention, in the solvent after wet pulverization, the volume-based cumulative 90% particle size of the raw material mixed powder is preferably at most 2.0 μm, more preferably at most 1.5 μm, and the wet size is appropriately adjusted so as to fall within this range. Conditions for crushing. Cumulative 90% particle size is obtained by laser diffraction/scattering method. Water was used as the dispersion medium, and the refractive index was set to 1.800 for measurement.

In addition, in the present invention, dry mixing may be performed before wet pulverization. When part or all of the above-mentioned raw materials are mixed by dry method and then mixed by wet method, the burden on the wet method can be reduced. For dry mixing, known mixers and dry pulverizers can be used. For example, dry jet mills, hammer mills, dry bead mills, screw mills, dry ball mills can be used. As the dry pulverizer, for example, impact pulverizers such as hammer mills and pin mills, grinding pulverizers such as roller mills and pulverizers, and jet pulverizers such as dry jet mills can be used.

After the raw materials are mixed by the wet pulverization method, filter drying and spray drying can be performed as needed. Moreover, it can also be granulated and/or shaped as needed, and it can also grind|pulverize suitably with the said dry grinder.

Next, the aforementioned raw material mixture is fired. The firing temperature can be properly set in the range where the BET specific surface area of the fired and crushed and pulverized pigments can be adjusted within the aforementioned range, preferably higher than 1100°C, more preferably in the range of 1100~1300°C . If it is this range, it will become easy to obtain the black near-infrared reflective pigment which has the said crystal phase or BET specific surface area. Since the BET specific surface area of the pigment fired by the above-mentioned added elements or the sintering treatment agent described later varies somewhat, it only needs to be finely adjusted based on the above-mentioned temperature range. In particular, it is more preferably in the range of 1180~1250°C.

The environment during firing can be carried out in any environment. Among them, firing in an oxygen-containing environment is preferable because sufficient near-infrared reflection properties can be maintained, and firing in air is more preferable.

The firing time can be appropriately set. If it is 0.5 to 24 hours, it is easy to obtain a black near-infrared reflective pigment having the aforementioned crystal phase or BET specific surface area. Since the BET specific surface area of the pigment fired by the above-mentioned added elements or the later-mentioned firing treatment agent etc. fluctuates to some extent, it only needs to be finely adjusted appropriately. Especially preferably, it is 1.0 to 12 hours. Although it can also be more than 24 hours, it is not economical.

Firing can use known equipment. As a firing apparatus, an electric furnace, a rotary kiln, etc. are mentioned, for example.

The fired pigments can be disintegrated and pulverized as needed. For disintegration and pulverization, the aforementioned dry pulverizer can be used.

(A) Preferred Production Method 1 (addition of firing treatment agent) In order to make the aforementioned firing reaction more uniform, or to make the particle size of the black near-infrared reflective pigment more uniform, it is also possible to add a firing agent to the mixture of raw material compounds. into a treatment agent (grain size regulator) and fired. As these sintering agents, for example, silicon compounds such as alkali metal compounds, silicon oxide, and silicate, tin compounds such as tin oxide, tin hydroxide, etc., or the periodicals of the aforementioned boron, aluminum, gallium, indium, etc., can also be used. Compounds of Group 13 in Table, but not limited thereto, various inorganic compounds or organic compounds can be used. The addition amount of a firing treatment agent (grain size regulator) can be set suitably, but it is preferable that it is an amount of the grade which does not reduce near-infrared reflection performance. In particular, it is preferable to add an alkali metal compound to a mixture of raw material compounds and bake it, since it is easier to obtain a black near-infrared reflective pigment with a more uniform particle size. Furthermore, when an alkali metal compound is added, there is also an advantage that pulverization after firing is relatively easy. Also, when the alkali metal compound remained in the obtained black near-infrared reflective pigment, no adverse effect on the near-infrared energy was seen, and it could be removed by washing and dissolving. As the alkali metal compound, potassium compounds such as potassium chloride, potassium sulfate, potassium nitrate, and potassium carbonate, sodium compounds such as sodium chloride, sodium sulfate, sodium nitrate, and sodium carbonate, lithium chloride, lithium sulfate, and lithium nitrate can be used. , lithium compounds such as lithium carbonate, etc. The amount of _the alkali metal compound to _be added _is preferably 0.01 to 15 parts by mass, more preferably 0.1 ~6 parts by mass.

(B) Preferred manufacturing method 2 (re-firing) The black near-infrared reflective pigment produced by the present invention can also be used for re-firing. It is preferable because the crystallinity of the composite oxide can be further improved, thereby suppressing the dissolution of calcium elements, manganese elements, etc. in water. The refiring temperature is preferably in the range of 200-1250°C, more preferably in the range of 400-1230°C. The environment for re-firing can be carried out in any environment. In order to maintain sufficient near-infrared reflection, it is better to fire in the air. The refiring time can be appropriately set, preferably 0.5 to 24 hours, more preferably 1.0 to 12 hours.

(C) Preferred Production Method 3 (Surface Treatment) In the present invention, the step of coating the surface of the black near-infrared reflective pigment particles with an inorganic compound and/or an organic compound may also be performed. Thereby, when used in coatings, inks, plastics, ceramics, electronic materials, etc., it can improve the dispersibility of the prepared solvents and resins. The inorganic compound is preferably at least one compound selected from silicon, zirconium, aluminum, titanium, antimony, phosphorus and tin, more preferably oxides, hydrated oxides or oxides of silicon, zirconium, aluminum, titanium, antimony and tin. The compound of hydroxide, phosphorus is more preferably phosphoric acid or a compound of phosphate. As organic compounds, for example, organosilicon compounds, organometallic compounds, polyhydric alcohols, alkanolamines or their derivatives, higher fatty acids or their metal salts, higher hydrocarbons or their derivatives, etc. can be used. Choose at least one.

The coating of the aforementioned inorganic compound can further improve the water dissolution resistance or acid resistance of the black near-infrared reflective pigment obtained by the method of the present invention. From this point of view, oxides, hydrated oxides, or hydroxides of silicon and aluminum are particularly preferred. The oxide, hydrated oxide or hydroxide of silicon (hereinafter sometimes referred to as silicon oxide) is more preferably one that forms high-density silicon oxide or porous silicon oxide. Corresponding to the pH range of the silicon oxide coating treatment, the coated silicon oxide becomes porous or non-porous (high density), but if it is high-density silicon oxide, it is easy to form a dense coating, so the near-infrared reflective pigment is dissolved in water It is preferable because of its high inhibitory effect on sex. Therefore, the first coating layer of high-density silicon oxide may exist on the particle surface of the black near-infrared reflective pigment, and the second coating layer of porous silicon oxide or aluminum oxide, hydrated oxide, or hydroxide may exist thereon. (hereinafter sometimes referred to as alumina). Silicon oxide coating can be observed by electron microscope. The coating amount of the inorganic compound can be appropriately set, for example, it is preferably 0.1-50% by mass, more preferably 1.0-20% by mass for near-infrared reflective pigments. The amount of the inorganic compound can be measured by common methods such as fluorescent X-ray analysis and ICP emission analysis.

As a method of coating the particle surface of the black near-infrared reflective pigment with an inorganic compound or an organic compound, conventional surface treatment methods such as titanium dioxide pigments can be used. Specifically, it is preferable to add an inorganic compound or an organic compound to the slurry of the black near-infrared reflective pigment and coat it, and it is more preferable to neutralize and precipitate the inorganic compound or organic compound in the slurry and coat it. In addition, it is also possible to add and mix an inorganic compound or an organic compound to the powder of the black near-infrared reflective pigment and coat it.

Specifically, when coating the particle surface of a black near-infrared reflective pigment with high-density silicon oxide, first adjust the water-based slurry of the black near-infrared reflective pigment with an alkali compound (such as sodium hydroxide, potassium hydroxide) or ammonia. After the pH is 8 or more, preferably 8 to 10, it is heated to 70°C or more, preferably 70 to 105°C. Next, add silicate to the aqueous slurry of black near-infrared reflective pigment. Various silicates such as sodium silicate and potassium silicate can be used as the silicate. The addition of silicate is usually carried out for more than 15 minutes, more preferably for more than 30 minutes. Next, after adding the silicate, stir and mix more thoroughly if necessary, and then neutralize with acid while maintaining the temperature of the slurry at preferably 80°C or higher, more preferably 90°C or higher. Examples of the acid used here are sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid, etc., thereby adjusting the pH of the slurry to preferably 7.5 or less, more preferably 7 or less, and coating the particle surface of the black near-infrared reflective pigment High-density silicon oxide.

Also, when coating the particle surface of the black near-infrared reflective pigment with porous silicon oxide, first add an acid such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, acetic acid, etc. to the aqueous slurry of the black near-infrared reflective pigment to adjust the pH to 1~4 , preferably 1.5~3. It is better to adjust the slurry temperature to 50~70°C. Next, silicate and acid are added while maintaining the pH of the slurry in the aforementioned range to form a coating of porous silicon oxide. Various silicates such as sodium silicate and potassium silicate can be used as the silicate. The addition of silicate is usually carried out for more than 15 minutes, more preferably for more than 30 minutes. Next, after adding the silicate, add an alkali compound as needed to adjust the pH of the slurry to about 6~9, and coat the particle surface of the black near-infrared reflective pigment with porous silicon oxide.

On the other hand, when coating the particle surface of the black near-infrared reflective pigment with alumina, the slurry of the black near-infrared reflective pigment is first neutralized to a pH of 8 to 9 with an alkali such as sodium hydroxide, and then heated to 50 The temperature above ℃, and secondly, it is preferable to simultaneously add the aluminum compound and the acidic aqueous solution in parallel. Aluminates such as sodium aluminate and potassium aluminate are preferably used as the aluminum compound, and aqueous solutions of sulfuric acid, hydrochloric acid, and nitric acid are preferably used as the acidic aqueous solution. The so-called simultaneous parallel addition refers to a method in which each of the aluminum compound and the acidic aqueous solution is continuously or intermittently added to the reactor in small amounts. Specifically, it is preferable to simultaneously add both for about 10 minutes to 2 hours while maintaining the pH in the reactor at 8.0 to 9.0. After adding the aluminum compound and the acidic aqueous solution, it is preferable to further add an acidic aqueous solution to adjust the pH to about 5 to 6.

When the black near-infrared reflective pigment coated with the above-mentioned inorganic compound is fired again, the crystallinity of the black near-infrared reflective pigment becomes higher, and the water dissolution resistance or acid resistance can be further improved. The refiring temperature is preferably in the range of 200-1250°C, more preferably 400-1230°C. The environment for re-firing can be carried out in any environment, but in order to maintain sufficient near-infrared reflection, it is better to fire in the air. The refiring time can be appropriately set, but is preferably 0.5 to 24 hours, more preferably 1.0 to 12 hours.

The black near-infrared reflective pigment obtained by the above production method can be used in various forms such as powder or molded body. When used as a powder, the particle size can be appropriately pulverized as necessary, and when used as a molded body, the powder can be made into an appropriate size and shaped into a shape. As the pulverizer, for example, impact pulverizers such as hammer mills and pin mills, pulverizers such as roll mills and pulverizers, and jet pulverizers such as jet mills can be used. As the molding machine, widely used molding machines such as extrusion molding machines and granulators can be used.

The black near-infrared reflective pigment obtained by the production method of the present invention is a material having sufficient near-infrared reflective performance, but it can be used in combination with other compounds having infrared reflective performance. In this way, the reflection energy of near-infrared rays can be further improved, and the reflection energy of a specific wavelength can be supplemented. Compounds having infrared reflective properties have been used in the past. Examples thereof include inorganic compounds such as titanium dioxide, iron-chromium, manganese-bismuth, and yttrium-manganese. The type and mixing ratio of the compound having near-infrared reflective performance can be appropriately selected according to the application.

The black near-infrared reflective pigment obtained by the production method of the present invention can also be mixed with other pigments. For example, it may have a color such as an intermediate color of red, yellow, green, or blue by making the black degree stronger, or toning it to gray. As the aforementioned pigment, inorganic pigments, organic pigments, lake pigments and the like can be used. Specifically, examples of inorganic pigments include white pigments such as titanium dioxide, zinc white, and precipitated barium sulfate, red pigments such as iron oxide, blue pigments such as ultramarine blue and cyanine (potassium ferricyanide), and black pigments such as carbon black. Pigment, aluminum powder and other pigments. Examples of organic pigments include organic compounds such as anthraquinone, perylene, phthalocyanine, azo-based, azomethyleneazo-based, and the like. The type of pigment and the mixing ratio can be selected appropriately according to the color and hue.

The black near-infrared reflective pigment obtained by the production method of the present invention can be used as a solvent dispersion. As the solvent, inorganic solvents such as water, organic solvents such as alcohols, alkanes, glycols, ethers, ketones, benzenes, acetates, and mixed solvents of inorganic solvents and organic solvents can be used. The concentration of the black near-infrared reflective pigment can be adjusted appropriately, preferably about 1~1000g/L. Dispersants, pigments, fillers, aggregates, tackifiers, flow control agents, leveling agents, hardeners, crosslinking agents, hardening catalysts, etc. can be formulated in the solvent dispersion. When producing the solvent dispersion, it can be carried out by conventional methods, and the black near-infrared reflective pigment is preferably dispersed in the solvent with a wet pulverizer. Conventional machines can be appropriately used as the wet pulverizer. Wet pulverizers using media such as bead mills, sand mills, and medium agitation mills, or agitation mills, disc mills, spiral mills, etc. can be used. Wet pulverizers such as jet mills that do not use media. In the present invention, in order to fully disperse the black near-infrared reflective pigment, it is preferable to use a wet pulverizer as a medium.

The black near-infrared reflective pigment obtained by the production method of the present invention can be used as a paint. Coatings contain components called inks or inks. Also, it can be used as a resin composition. Also, it can be used as a fiber composition. Moreover, the aforementioned paint can also be coated on a substrate to be used as a near-infrared reflective material.

When the black near-infrared reflective pigment obtained by the production method of the present invention is contained in a resin of a plastic molding such as paint, ink, or film, it can be a composition utilizing its excellent near-infrared reflective performance. In the paint, ink, or resin composition, the black near-infrared reflective pigment may be contained in any amount relative to the resin, preferably at least 0.1% by mass, more preferably at least 1% by mass, more preferably at least 10% by mass. In addition, composition-forming materials used in various fields can also be formulated, and various additives can also be formulated.

Specifically, when preparing paint or ink, in addition to coating film forming materials or ink film forming materials, solvents, dispersants, pigments, fillers, aggregates, thickeners, flow control agents, and leveling agents can be formulated , hardener, crosslinking agent, catalyst for hardening, etc. As the coating film forming material, organic components such as acrylic resins, alkyd resins, urethane resins, polyester resins, amino resins, organic silicates, organic titanates, Inorganic components of cement, gypsum, etc. Urethane-based resins, acrylic resins, polyamide-based resins, vinyl acetate-based resins (copolymerized resins of vinyl chloride and vinyl acetate), and propylene chloride-based resins can be used as ink film forming materials. wait. In these coating film forming materials and ink film forming materials, various kinds of thermosetting resins, room temperature curing resins, ultraviolet curable resins, etc. can be used without limitation, and ultraviolet curable resins of monomers or oligomers are used, When a photopolymerization initiator or a photosensitizer is formulated and cured by irradiation with ultraviolet light after coating, it is preferable to obtain a coating film with excellent hardness or adhesion without causing a thermal load on the substrate.

A near-infrared reflective material can be produced by coating the aforementioned paint on a substrate. The near-infrared reflective material can be used as a shielding material for infrared rays, and can also be used as a heat shielding material. That is, it can be used as an infrared reflection material. Various materials and materials can be used as the base material. Specifically, various building materials and civil engineering materials can be used, and the manufactured near-infrared reflective material can be used as roofing materials, wall materials, or floor materials for houses or factories, or as paving materials for roads or sidewalks. The thickness of the near-infrared reflective material can be set arbitrarily according to various purposes. For example, when used as a roofing material, it is about 0.1~0.6mm, preferably 0.1~0.3mm; when used as a paving material, it is about 0.5~5mm, preferably 1~5mm. When coating on the base material, it can be applied by coating, by blowing, or by trowel. After coating, it can also be dried, grilled, and preserved as needed.

When making the resin composition, in addition to the resin, pigments, dyes, dispersants, slip agents, antioxidant materials, ultraviolet absorbers, light stabilizers, antistatic agents, flame retardants, bactericides, etc. The black near-infrared reflective pigment obtained by the method is kneaded together and formed into any shape such as film, flake, plate, etc. As the resin, polyolefin resin, polystyrene resin, polyester resin, acrylic resin, polycarbonate resin, fluorine resin, polyamide resin, cellulose resin, polylactic acid resin, etc. can be used. Thermosetting resins such as thermoplastic resins, phenolic resins, and urethane resins. These resin compositions can be formed into arbitrary shapes such as films, sheets, and plates, and can be used as near-infrared reflective materials for industrial, agricultural, and home use. In addition, it can also be used as a heat-shielding material for shielding infrared rays.

The fiber composition having the black near-infrared reflective pigment obtained by the production method of the present invention can impart near-infrared reflective energy to clothing, woven fabrics, non-woven fabrics, wallpapers, and the like. Known fibers can be used, such as cellulose regenerated fibers such as rayon, polyamide fibers such as nylon, polyester or acrylic fibers such as polyethylene terephthalate, and carbon fibers. The black near-infrared reflective pigment can be mixed in during fiber spinning, and can also be fixed on the spinning surface for use. These methods may suitably use the previous methods. Also, the black near-infrared reflective pigment may be contained in any amount in the fiber, preferably at least 0.1% by mass, more preferably at least 1% by mass.

Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is not limited to these Examples. [Example]

(Experiment 1) Example 1 Calcium carbonate CaCO ₃ (manufactured by Kamishima Chemical Co., Ltd.) 32.72 g, titanium dioxide (manufactured by Ishihara Sangyo Co., Ltd.) 13.04 g, manganese dioxide (manufactured by TOSOH Co., Ltd.) 14.12 g were separated, And feed it into a 220mL mayonnaise bottle, and then add 100g of glass beads and pure water, fully mix and pulverize with a paint shaker (time: 30 minutes). After drying this raw material mixture, it fired at 1200 degreeC for 4 hours. The fired product was disintegrated in an automatic mortar to obtain a sample A. The results of the analysis of sample A using a fluorescent X-ray analyzer (manufactured by RIGAKU Co., Ltd., RIX-2100) and a powder X-ray diffraction device (manufactured by RIGAKU Co., Ltd., Ultima IV) were obtained from ABO containing titanium, manganese and calcium. Type ₃ perovskite structure is composed of a single-phase complex oxide, and the atomic ratio (molar ratio) of manganese to titanium is expressed as [Mn]/[Ti], and its value is 1.00. And, when the particle size distribution of the raw material mixture after pulverization and mixing was measured using a laser diffraction/scattering particle size distribution analyzer (LA-910 manufactured by Horiba Co., Ltd.), the cumulative 90% particle size (volume basis) was 1.29 μm.

Example 2 A sample B was obtained in the same manner as in Example 1 except that the firing temperature was 1180°C. Sample B was analyzed in the same way as in Example 1. It was formed from a single phase of composite oxides with an ABO ₃ -type perovskite structure containing titanium, manganese, and calcium. The atomic ratio (molar ratio) of manganese to titanium was [ Mn]/[Ti] is expressed as 1.00.

Example 3 A sample C was obtained in the same manner as in Example 1 except that the firing temperature was 1300°C. Sample C was analyzed in the same manner as in Example 1. It was formed by a single phase of composite oxides with an ABO ₃ -type perovskite structure containing titanium, manganese, and calcium. The atomic ratio (molar ratio) of manganese to titanium was [ Mn]/[Ti] is expressed as 1.00.

Comparative Example 1 32.72 g of calcium carbonate, 13.04 g of titanium dioxide, and 14.12 g of manganese dioxide were divided and fully mixed with an automatic mortar, and fired at 1150° C. for 4 hours. The fired product was disintegrated in an automatic mortar to obtain a sample D. Sample D was analyzed in the same manner as in Example 1. It was formed from a single phase of composite oxides with an ABO _3- type perovskite structure containing titanium, manganese, and calcium. The atomic ratio (molar ratio) of manganese to titanium was [ Mn]/[Ti] is expressed as 1.00.

Comparative example 2 Except having set the calcination temperature to 1180 degreeC, it carried out similarly to the comparative example 1, and obtained the sample E. Sample E was analyzed in the same way as in Example 1. It was formed from a composite oxide single phase of ABO ₃ type perovskite structure containing titanium, manganese and calcium. The atomic ratio (molar ratio) of manganese to titanium was [ Mn]/[Ti] is expressed as 1.00.

Comparative Example 3 Except that the firing temperature was 1200° C., it was carried out in the same manner as in Comparative Example 1, and a sample F was obtained. Sample F was analyzed in the same manner as in Example 1. It was formed from a single phase of composite oxides with an ABO ₃ -type perovskite structure containing titanium, manganese, and calcium. The atomic ratio (molar ratio) of manganese to titanium was [ Mn]/[Ti] is expressed as 1.00.

Comparative example 4 Except having set the calcination temperature to 1160 degreeC, it carried out similarly to Example 1, and obtained the sample G. Sample G was analyzed in the same manner as in Example 1. It was formed from a single-phase composite oxide of ABO ₃ type perovskite structure containing titanium, manganese and calcium. The atomic ratio (molar ratio) of manganese to titanium was [ Mn]/[Ti] is expressed as 1.00.

Comparative Example 5 A sample H was obtained in the same manner as in Example 1 except that the firing temperature was 1140°C. Sample H was analyzed in the same way as in Example 1. It was formed from a single phase of composite oxides with an ABO _3- type perovskite structure containing titanium, manganese, and calcium. The atomic ratio (molar ratio) of manganese to titanium was [ Mn]/[Ti] is expressed as 1.00.

(Evaluation 1) BET specific surface area measurement The BET specific surface area of each sample was measured. The measurement was calculated by the BET one-point method of nitrogen adsorption using Macsorb HM Model 1220 (manufactured by MOUNTECH).

(Evaluation 2) Evaluation of acid resistance First, the sample, polyester resin (BYRON GK-19CS manufactured by Toyobo Co., Ltd.) and melamine resin (SUPER BECKAMINE L-109 manufactured by DIC Co., Ltd.) were adjusted to P/B (pigment / resin weight ratio) = 0.8, SVC (solid volume concentration) = 44.7% to make coatings. The prepared paint was coated on a steel plate with a #15 bar coater, and baked at 210°C for 10 minutes to make a coated film. The produced coated film was immersed in 5% sulfuric acid for 48 hours. The 60° gloss before and after immersion is measured for the coating film coated on the steel plate, and the gloss change (gloss retention rate) of the initial coating film is evaluated. In addition, the color change of the coated film after dipping in acid was compared with that of the non-impregnated coated film. Both are used as indicators of acid resistance. A gloss meter (VG-2000 manufactured by Nippon Denshoku Kogyo Co., Ltd.) was used to measure the 60° gloss. The standard for color change observation is "○" means almost no change, "△" means clear color change, and "×" means significant color change.

Table 1 shows the evaluation results for samples A to H. A graph in which the specific surface area is plotted together with the gloss retention is shown in FIG. 1 . As the specific surface area decreases, the gloss retention rate after sulfuric acid immersion increases, and each of dry grinding and wet grinding is in a roughly linear relationship within the raw material mixing method. In addition, when the dry pulverization method and the wet pulverization method were compared with the same specific surface area, the gloss retention increased by about 20% by mixing in the wet method. That is, the balance between specific surface area and gloss retention can be shifted to the high characteristic side. For color change, reduce it by mixing with wet pulverization. Compared with dry mixing and grinding, wet mixing and grinding can reduce the agglomeration of each raw material powder, especially manganese dioxide raw material powder. Because it can uniformly mix raw materials with different particle sizes (calcium compound, manganese compound, titanium compound), it is considered advantageous. Improve acid resistance. If the specific surface area is less than 3m ² /g, it can be expected to maintain a gloss retention rate of 40% or more. If the specific surface area is 2.6m ² /g or less, a gloss retention rate of 50% or more can be seen, and no significant discoloration will be caused, so it is preferable. When the specific surface area is 2.1 m ² /g or less, a gloss retention rate of 70% or more is seen, and discoloration is hardly seen, which is more preferable.

(Experiment 2) Example 4 In addition to the same 32.72g of calcium carbonate, 13.04g of titanium dioxide, and 14.12g of manganese dioxide as those used in Experiment 1, 0.29g of aluminum hydroxide (manufactured by KISHIDA Chemical Co., Ltd.) and bismuth oxide were separated (manufactured by Kanto Chemical Co., Ltd.) 0.41g, sodium chloride (manufactured by Wako Pure Chemical Industries Co., Ltd.) 0.60g, put in a 220mL mayonnaise bottle, add 100g of glass beads and pure water, and mix well with a paint shaker and crushing (time: 30 minutes). After drying this raw material mixture, it fired at 1180 degreeC for 4 hours. The fired product was disintegrated in an automatic mortar to obtain a sample I. The result of analyzing sample I in the same manner as in Example 1 is that it is formed by a single-phase composite oxide of the ABO ₃ -type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth. The atomic ratio of manganese to titanium (molar ratio ) is represented by [Mn]/[Ti] as 1.00, when the atomic ratio (molar ratio) of aluminum to titanium and manganese is represented by [Al]/([Ti]+[Mn]), its value is 0.011, bismuth and The atomic ratio (molar ratio) of titanium and manganese is 0.0053 expressed by [Bi]/([Ti]+[Mn]). The sodium system contains 0.13% by mass as Na ₂ O.

Example 5 A sample J was obtained in the same manner as in Example 4, except that the amount of aluminum hydroxide was 0.44 g and the firing temperature was 1150°C. The result of analyzing sample J in the same manner as in Example 1 is that it is composed of a single phase of composite oxides with an ABO ₃ -type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth. The atomic ratio of manganese to titanium (molar ratio ) is represented by [Mn]/[Ti] as 1.00, the atomic ratio (molar ratio) of aluminum to titanium and manganese is represented by [Al]/([Ti]+[Mn]) as 0.017, and the ratio of bismuth to titanium and manganese The atomic ratio (molar ratio) was 0.0053 expressed by [Bi]/([Ti]+[Mn]).

Example 6 A sample K was obtained in the same manner as in Example 5 except that the firing temperature was 1200°C. The result of analyzing the sample K in the same manner as in Example 1 is that it is composed of a single phase of a composite oxide of the ABO ₃ type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth. The atomic ratio of manganese to titanium (molar ratio ) is represented by [Mn]/[Ti] as 1.00, the atomic ratio (molar ratio) of aluminum to titanium and manganese is represented by [Al]/([Ti]+[Mn]) as 0.017, and the ratio of bismuth to titanium and manganese The atomic ratio (molar ratio) was 0.0053 expressed by [Bi]/([Ti]+[Mn]).

Example 7 A sample L was obtained in the same manner as in Example 6 except that the amount of aluminum hydroxide was 0.88 g. The result of analyzing the sample L in the same manner as in Example 1 is that it is formed by a single phase of a composite oxide of the ABO ₃ type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth. The atomic ratio of manganese to titanium (molar ratio ) is represented by [Mn]/[Ti] as 1.00, the atomic ratio (molar ratio) of aluminum to titanium and manganese is represented by [Al]/([Ti]+[Mn]) as 0.034, and the ratio of bismuth to titanium and manganese The atomic ratio (molar ratio) was 0.0053 expressed by [Bi]/([Ti]+[Mn]).

Example 8 A sample M was obtained in the same manner as in Example 6 except that the amount of aluminum hydroxide was 1.50 g. The result of analyzing the sample M in the same manner as in Example 1 is that it is composed of a single phase of a composite oxide of the ABO ₃ -type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth. The atomic ratio of manganese to titanium (molar ratio ) is represented by [Mn]/[Ti] as 1.00, the atomic ratio (molar ratio) of aluminum to titanium and manganese is represented by [Al]/([Ti]+[Mn]) as 0.055, and the ratio of bismuth to titanium and manganese The atomic ratio (molar ratio) was 0.0053 expressed by [Bi]/([Ti]+[Mn]).

Example 9 A sample N was obtained in the same manner as in Example 6 except that the amount of aluminum hydroxide was 3.00 g. The result of analyzing the sample N in the same manner as in Example 1 is that it is composed of a single phase of a composite oxide of the ABO ₃ type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth. The atomic ratio of manganese to titanium (molar ratio ) is represented by [Mn]/[Ti] as 1.00, the atomic ratio (molar ratio) of aluminum to titanium and manganese is represented by [Al]/([Ti]+[Mn]) as 0.11, and the ratio of bismuth to titanium and manganese The atomic ratio (molar ratio) was 0.0053 expressed by [Bi]/([Ti]+[Mn]).

Example 10 A sample O was obtained in the same manner as in Example 6 except that bismuth oxide and sodium chloride were not used. The result of analyzing sample O in the same manner as in Example 1 is that it is composed of a single phase of composite oxides with an ABO ₃ -type perovskite structure containing titanium, manganese, calcium and aluminum. The atomic ratio (molar ratio) of manganese to titanium is [Mn]/[Ti] is expressed as 1.00, and the atomic ratio (molar ratio) of aluminum to titanium and manganese is expressed as [Al]/([Ti]+[Mn]) as 0.017.

Example 11 A sample P was obtained in the same manner as in Example 5 except that the firing temperature was 1300°C. The result of analyzing the sample P in the same manner as in Example 1 is that it is composed of a single phase of a composite oxide of the ABO ₃ -type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth. The atomic ratio of manganese to titanium (molar ratio ) is represented by [Mn]/[Ti] as 1.00, the atomic ratio (molar ratio) of aluminum to titanium and manganese is represented by [Al]/([Ti]+[Mn]) as 0.017, and the ratio of bismuth to titanium and manganese The atomic ratio (molar ratio) was 0.0053 expressed by [Bi]/([Ti]+[Mn]).

Example 12 A sample Q was obtained in the same manner as in Example 7 except that the firing temperature was set to 1300°C. The result of analyzing the sample Q in the same manner as in Example 1 is that it is composed of a single phase of a composite oxide of the ABO ₃ -type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth. The atomic ratio of manganese to titanium (molar ratio ) is represented by [Mn]/[Ti] as 1.00, the atomic ratio (molar ratio) of aluminum to titanium and manganese is represented by [Al]/([Ti]+[Mn]) as 0.034, and the ratio of bismuth to titanium and manganese The atomic ratio (molar ratio) was 0.0053 expressed by [Bi]/([Ti]+[Mn]).

Example 13 A sample R was obtained in the same manner as in Example 8 except that the firing temperature was 1300°C. The result of analyzing the sample R in the same manner as in Example 1 is that it is composed of a single phase of a composite oxide with an ABO ₃ -type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth, and [Mn]/[Ti] is 1.00. [Al]/([Ti]+[Mn]) was 0.055, and [Bi]/([Ti]+[Mn]) was 0.0053.

Example 14 A sample S was obtained in the same manner as in Example 9 except that the firing temperature was 1300°C. The result of analyzing the sample S in the same manner as in Example 1 is that it is composed of a single phase of a composite oxide of the ABO ₃ type perovskite structure containing titanium, manganese, calcium, aluminum, and bismuth. The atomic ratio of manganese to titanium (molar ratio ) is represented by [Mn]/[Ti] as 1.00, the atomic ratio (molar ratio) of aluminum to titanium and manganese is represented by [Al]/([Ti]+[Mn]) as 0.11, and the ratio of bismuth to titanium and manganese The atomic ratio (molar ratio) was 0.0053 expressed by [Bi]/([Ti]+[Mn]).

(Evaluation 3) Degree of dispersion First, adjust the alkyd resin (manufactured by DIC Co., Ltd., ALUKIDIR J-524IM) and melamine resin (manufactured by DIC Co., Ltd., ALUKIDIR J-820) so that PVC (pigment volume concentration) = 19.2 , P/B (pigment/resin weight ratio) = 0.8, SVC (solid volume concentration) = 46.0% to make coatings. Based on JIS K 5600-2-5, the prepared paint was evaluated using a particle size meter with a maximum depth of 100 μm to evaluate the depth of dense particle generation. This evaluation was performed three times, and the average value of the three times was taken as the degree of dispersion (μm). The smaller the value of the degree of dispersion, the higher the dispersibility of the pigment particles in the paint.

(Evaluation 4) Reflectance of powder The near-infrared reflectance of powder was measured using an ultraviolet-visible-near-infrared spectrophotometer (V-670 manufactured by Nippon Denshoku Industries Co., Ltd.). Put the sample into the dedicated measurement unit for powder directly, and measure the spectral reflectance in the range of 300~2500nm.

Table 2 shows the specific surface area of each sample, the evaluation results of acid resistance (color change and gloss change rate), the degree of dispersion, and the measurement results of reflectance at a wavelength of 1200 nm. Adding Al and Bi and firing as in samples I~N can make the acid resistance effect greater than that of sample A. It can be seen that when the atomic ratio (molar ratio) [Al]/([Ti]+[Mn]) of aluminum to titanium and manganese exceeds 0.01, the effect of improving acid resistance increases, and especially when it exceeds 0.015, it shows high acid resistance. However, when the above-mentioned [Al]/([Ti]+[Mn]) exceeds 0.1 and increases, a color change is seen and the degree of dispersion also becomes high. In addition, when sample K was compared with O, the acid resistance was improved, and the acid resistance improvement effect by adding Bi was also confirmed.

As shown in Table 2, among the samples obtained by the production method of the present invention, the specific surface area of samples K~N is also more than 1.6m ² /g and less than 3.0m ² /g, so the dispersion measured by the particle size meter is below 20μm, and the dispersion Especially excellent, can be well dispersed in the paint.

The chart obtained by plotting the specific surface area and the powder reflectance at a wavelength of 1200nm in Fig. 2 shows the spectral reflectance curves of representative samples K, L, P, and Q in Fig. 3 . As can be seen from Figure 2, the reflectance characteristics of the powder at a wavelength of 1200nm have an inflection point near the specific surface area of 1.5m ² /g, so that the reflectance of the powder tends to increase when the specific surface area is high. Samples K~N with a specific surface area of 1.5m ² /g or more are compared with samples P~S with the same composition and a specific surface area of less than 1.5m ² /g. Points 7~9 indicate high reflectance, which shows that near-infrared ray reflection High rate. Moreover, as shown in Figure 3, the reflectance in the visible light region is suppressed to be low because it is black, but above about 900nm, it can be seen that the reflectance is higher by comparing samples K and L with samples P and Q.

(Evaluation 5) Reflectance of the coating film The coating was produced in the same procedure as in Evaluation 3. The paint was coated on black and white recording paper with a #30 bar coater, and baked at 110°C for 30 minutes to make a coating film. The spectroscopic reflectance of the coating film on the black was measured using an ultraviolet-visible-near-infrared spectrophotometer (Nippon Denshoku Industries Co., Ltd. V-670) in the range of 300 to 2500 nm. The measured data is calculated using the weighting coefficients described in JIS K 5602 to calculate the solar reflectance (%) of the coating film.

Fig. 4 shows the spectral reflectance curves of coating films prepared using samples K, L, P, and Q. Because it is black, the reflectance in the visible light region is suppressed to be low, but above about 900nm, it can be known that the reflectance is higher by comparing samples K and L with samples P and Q.

Table 3 shows the solar reflectance of the coating film calculated from the weighting coefficients described in JIS K 5602. Similar to the reflectance of the powder, the reflectance in the visible light region is suppressed to be low because it is black, but in the range of 780~2500nm, comparing the samples K and L with the samples P and Q, it can be seen that the near-infrared reflection characteristics are excellent.

The blackness of samples A~S is measured by Hunter Lab color space (Lab color system), and the lightness index L value of any sample is below 20. [Industrial availability]

The present invention can improve the acid resistance of the black near-infrared reflective pigment containing at least calcium element, titanium element and manganese element, and can be used in various applications. In particular, it is effective in alleviating the heat island phenomenon or improving the cooling efficiency of buildings in summer, and has industrial applicability.

FIG. 1 is a graph showing the relationship between the specific surface area and gloss retention of each sample in Experiment 1. FIG. Figure 2 is a graph showing the relationship between the specific surface area of each sample in Experiment 2 and the reflectance at a wavelength of 1200nm. Figure 3 is the spectral reflectance curves of the powders of samples K, L, P, and Q in Experiment 2. Figure 4 is the spectral reflectance curves of the coating films manufactured using the samples K, L, P, and Q of Experiment 2.

Claims (7)

A black near-infrared reflective pigment, which contains at least calcium element, titanium element, manganese element, and bismuth element, and has a perovskite (perovskite) phase as the main phase, and the atomic content of bismuth element ([Bi]) is relative to that of titanium element The atomic ratio ([Bi]/([Ti]+[Mn])) of the sum of the atomic content of manganese ([Ti]) and the atomic content of manganese ([Mn]) is not less than 0.002 and not more than 0.02. The black near-infrared reflective pigment according to claim 1, which at least contains calcium, titanium, manganese, bismuth, and aluminum, and has a perovskite phase as the main phase. Such as the black near-infrared reflective pigment of claim 2, wherein the atomic ratio of the atomic content of the aluminum element ([Al]) to the sum of the atomic content of the titanium element ([Ti]) and the atomic content of the manganese element ([Mn]) ([Al]/([Ti]+[Mn])) is 0.1 or less. The black near-infrared reflective pigment as claimed in claim 1 has a BET specific surface area of 1.0 m ² /g or more and less than 3.0 m ² /g. A method for producing a black near-infrared reflective pigment, which is to mix at least calcium compound, titanium compound, manganese compound, and bismuth compound by a wet pulverization method, and fire the black near-infrared reflective pigment at a temperature higher than 1100°C In the manufacturing method, the aforementioned black near-infrared reflective pigment is based on a perovskite phase, the BET specific surface area is not less than 1.0m ² /g and less than 3.0m ² /g, and the bismuth element in the aforementioned black near-infrared reflective pigment is Atomic ratio ([Bi]/([Ti]+[Mn])) of atomic content ([Bi]) to the sum of atomic content of titanium element ([Ti]) and manganese element ([Mn]) It is 0.002 or more and 0.02 or less. A method for producing a black near-infrared reflective pigment as claimed in claim 5, at least mixing and firing calcium compounds, titanium compounds, manganese compounds, bismuth compounds, and aluminum compounds by wet pulverization. The method for producing a black near-infrared reflective pigment according to claim 6, wherein in the black near-infrared reflective pigment, the atomic content of aluminum element ([Al]) is relative to the atomic content of titanium element ([Ti]) and the atomic content of manganese element The atomic ratio ([Al]/([Ti]+[Mn])) of the sum of ([Mn]) is 0.1 or less.

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